Eczema: Could it be Hereditary?

Eczema is a chronic inflammatory skin disease , characterised by red and warm lesions, varying in size and spread across the body. These are accompanied by intense itching. It's worth noting that eczema can affect almost all parts of the face and body. Within the lesions, there is a thickening of the skin, known as lichenification. Small vesicles filled with clear fluid then appear at the site of the red lesions, and eventually burst due to scratching. A crust then forms, which heals to varying degrees thereafter.

Eczema is often persistent. Between the flare-ups or outbreaks of eczema, there are periods of remission where the skin remains very dry (xerosis). However, eczema is considered a benign condition. Indeed, even though the itching it causes and its psychological impact cannot be overlooked, this disease does not pose a life-threatening risk to health. Moreover, appropriate management and following dermatological advice can limit its impact on the quality of life of those affected. Finally, it is important to emphasise that eczema is non-contagious.

In certain instances, eczema indeed has a hereditary component. According to numerous studies, 50 to 70% of children affected by eczema have a first-degree relative who has also been afflicted. This is then referred to as atopic eczema, meaning that the individuals affected have a predisposition to develop common allergies to pollen, dust or animal fur, for example. Several biological mechanisms play a role in this atopy.

One of the primary causes of atopic eczema is the mutation of the gene coding for filaggrin. In atopic individuals, this gene is often inactive. A study has indeed shown that a mutation of this gene in a pregnant woman results in a 50% increase in the risk of atopic dermatitis for the unborn child. Indeed, filaggrin is a protein of the stratum corneum that plays a crucial role in the proper functioning of the skin barrier. It is notably incorporated into the lipid envelope and also interacts with keratin filaments. A lack of filaggrin in the stratum corneum is associated with greater transepidermal water loss (TEWL) and a higher capacity for allergens to penetrate the skin. This skin is generally more dry, more permeable, and less protected.

Furthermore, it is estimated that approximately 70 to 80% of individuals with atopic eczema naturally produce an abnormally high amount of Immunoglobulin E (IgE), antibodies, in response to environmental allergens. When a person is sensitive to an allergen, their immune system produces specific IgE for that allergen. These IgE attach to receptors found on mast cells, immune cells primarily located in connective tissues. Consequently, any exposure to this allergen causes it to bind to the IgE and triggers the release of histamine, a chemical mediator, from the granules contained within the mast cells. This then initiates a cascade of reactions leading to the typical inflammation of eczema, characterised by redness and itching.

Note : not all forms of eczema are hereditary, for instance, consider contact eczema. Furthermore, even if your eczema has a genetic component, if you decide to have a child, they may not necessarily be affected.

• GOLDENBERG G. & al. Eczema. The Mount Sinai Journal of Medicine (2011).

• LEE Y.-A. & al. The genetics of the skin barrier in eczema and other allergic disorders. Current Opinion in Allergy and Clinical Immunology (2015).